Catalytic hydrodehalogenation of chlorinated ethylenes using palladium and hydrogen for the treatment of contaminated water

Article abstract of DOI:10.1016/0045-6535(95)00200-R

A kinetic model is presented for the catalytic hydrodehalogenation of chlorinated ethylenes using Pd and H"SUB 2" under water treatment conditions. All five chlorinated ethylenes, including tetrachloroethylene (PCE) and vinyl chloride, were completely removed from tap water within 10 minutes at room temperature by 0.5 g of 0.5% Pd on alumina and 0.1 atm H"SUB 2" . Ethane accounted for 55-85% of the mass balance in these systems. Palladium on granular carbon was also an effective catalyst. The transformation of PCE was first order with respect to both substrate and amount of metal. Addition of 10 mg/L of nitrite to the water decreased the rate constant by about 50%. Addition of nitrate or sulfate had smaller effect on the rate of PCE transformation; chloride had no effect. The presence of oxygen greatly reduced the amount of ethane produced regardless of the catalyst support. Bisulfide poisoned the catalyst. (from Authors)